Katalin V.-Balogh

Freshwater picocyanobacteria along a trophic gradient and light quality range

Picocyanobacterial abundance and their contribution to the total phytoplankton biomass, estimated as chlorophyll a, was investigated in 32 deep and shallow lakes. The lake series covered a wide range of natural and artificial lakes, from high altitude clear lakes and deep, large subalpine lakes through large shallow lakes, small reservoirs and fish ponds. The chlorophyll a concentrations ranged between 0.2 and 390 µg l-1. No simple relation existed between trophic state and the abundance of picocyanobacterial, mainly represented by Synechococcus spp. Below 10 µg Chl a l-1 the percentage contribution of picocyanobacteria biomass to total phytoplankton biomass exceeded 70% in some cases, whereas above 100 µg Chl a l-1, the highest contribution was only 10%. At low chlorophyll a concentrations phycoerythrin-rich picocyanobacteria (PE) dominated almost exclusively but their contribution never exceeded 10% of the total picocyanobacterial abundance when chlorophyll a concentration was higher than 50 µg l-1. Above this value there was high light attenuation and a shift of the maximum light penetration from the blue-green towards the red portion of the spectrum. In this underwater light climate phycocyanin-rich picocyanobacteria (PC) dominated. In the lakes chosen for their representation of ranges in trophy and light quality, PC cells prevailed over the PE when vertical attenuation coefficient of PAR was higher than 2.25 m-1 and red light penetrated farthest. PE cells were 100% when the vertical attenuation coefficient of PAR was lower than 0.55 m-1 and the green and blue were the most penetrating lights.

Heavy metals in animals of Lake Balaton

Abstract Hg, Cd, Cu, Pb, Zn, Fe and Mn concentrations were measured in Chironomidae larvae, Crustacea plankton, as well as in various organs of mussels and fishes collected from the open water area of Lake Balaton. The values were comparatively low. However, there were significant differences in the metal concentrations of species and tissue. Most Cd was found in the gill of Unio pictorum L., most Pb, Zn and Mn in the gill of Anodonta cygnea L., most Cu in Crustacea plankton and in the liver of Abramis brama L., and most Hg and Fe in Chironomidae larvae. Low concentrations occurred in fishes, the lowest in the flesh of Stizostedion lucioperca L. Accumulation of metals in organs as compared with their concentration in the lake water was in the range of 3.4 × 10 2 −2.6 × 10 3 for Hg; 7.0 × 10 2 −6.8 × 10 3 for Cd; 3.3 × 10 2 −9.7 × 10 3 for Cu; 6.9 × 10 2 −8.1 × 10 3 for Zn; 1.5 × 10 3 −2.4 × 10 4 for Pb; 3.5 × 10 2 −3.1 × 10 4 for Fe; and 5.0 × 10 1 −3.5 × 10 5 for Mn.

Characterizing the spectral reflectance of algae in lake waters with high suspended sediment concentrations

Remote sensing has the potential to provide truly synoptic views of water quality, the assessment of which is known to be affected by suspended sediment, phytoplankton biomass (chlorophyll a (Chl a) concentration) and dissolved organic carbon. These three components also control the spectral reflectance characteristics of waterbodies. This Letter uses in situ reflectance measurements of water in Lake Balaton on three different occasions, supplemented by controlled tank experiments, to characterize the influences of suspended sediment concentrations (SSC) and Chl a on spectral reflectance and simulated Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) response. The results confirm that Chl a cannot be estimated directly from Landsat reflectance data in waters characterized by heterogeneous SSC. However, principal component analysis (PCA) demonstrated that spectrally unique end‐members can be identified, indicating that a spectral linear mixture modelling approach combined with a multivariate regression analysis may be used to provide estimates of Chl a concentrations, which would be independent of SSC.

Size-selective filtration and taxon-specific digestion of plankton algae by silver carp (Hypophthalmichthys molitrix Val.)

A comparison of the composition of natural phytoplanktoncommunities with the gut content of silver carp (Hypophthalmichthys molitrix) showed that this fish speciescan nottake up algae smaller than 10 µm. The species compositionofalgal assemblages in the gut content of the silver carpusuallydiffers significantly from the composition of the >10 µmsizefraction of the natural phytoplankton assemblages. Thisdifferenceis mainly a result of the taxon selective digestion of silvercarp.In vitro experiments with digestive enzymes of thisspeciesresulted in a very fast (1–2 minutes) disintegration ofnon-mucilaginous cyanobacteria. The digestion of diatoms andcryptophytes was also effective, but mucilaginouscyanobacteria andgreen algae (Chlorococcales) proved practicallyindigestible.

Physiological background for using freshwater mussels in monitoring copper and lead pollution

In studying the effect of copper (10 ± 0.57 µg Cu l−1 and 100 ± 3.01 µg Cu l−1) and lead (50 ± 1.12 µg Pb l−1 and 500 ± 12.5 µg Pb l−1) on the filtration activity of Anodonta cygnea L. it was found that both heavy metals resulted in significant shortening of the active periods, but little change occurred in the length of the rest periods. The concentrations of copper and lead were measured in the gill, foot, mantle, adductor muscle and kidney for 840 hours of exposure to 10.9 ± 5 µg Cu l−1 and 57.0 ± 19 µg Pb l−1 as well as during subsequent depuration. Uptake was observed after 72 hours of exposure. The highest copper concentration (59.1 ± 16.2 µg Cu g−1) was measured at 672 h in the mantle, and the highest lead value (143 ± 26.1 µg Pb−1) was obtained in the kidney. Depuration of copper was fastest from the foot, and from the adductor muscle for lead. The gill had the longest half-depuration time (> 840 h for copper and > 672 h for lead).

The dynamics of mercury and cadmium uptake into different organs of Anodonta cygnea L.

Abstract The bioaccumulation of Hg and Cd into various organs of the freshwater mussel Anodonta cygnea was investigated during an 840 h experimental period. Parallel with the metal concentrations the periodicity of activity and the body weight of the animals were also checked. The accumulation of Hg in all of the investigated organs, and that of the Cd into the kidney have two phases, up to 24 h it was non linear, between 24 and 72 h it became linear in most organs up to 840 h, and could be characterized by a regression line. For Hg accumulation the gills while for Cd accumulation the kidney and viscera were exceptions, here saturation was observed after 504 and 672 h, respectively. The speed of Hg and Cd uptake was different in various organs of Anodonta cygnea. Into the kidney the accumulation of Hg was six times faster than that of Cd. As compared to the adductor muscles the Hg and Cd uptake of the kidney was 20 and 10 times faster, respectively. The factor of concentration was in all organs except adductor muscles over 1000, in case of the kidney the rate of bioconcentration for Hg reached nearly 100,000. The dry weight of organs dropped during the metal uptake by 20–60%, but no mortality was observed up to 840 h. In the presence of Hg and Cd the filtering activity of the mussels became reduced as a result of increase of inactive rest periods. Nevertheless, the decrease of activity did not prevent the linear uptake of metals into the animal

Heavy metal pollution from a point source demonstrated by mussel (Unio pictorum L.) at Lake Balaton, Hungary.

Few studies are concerned with heavy metal pollution caused by the use of various paints in water ecosystems. In a study on the content of metals in dockyard sediments, elevated levels of Cu and Zn from antifouling paints, and Pb from anticorrosive and primer paints were reported. In the present work, a study was performed close to a sailing boat harbor of heavy metal pollution using biological samples. The concentrations of Cu, Zn, Cd and PB were determined in the organs of freshwater mussel (Unio pictorum L.) by AAS technique.

Cadmium uptake and depuration in different organs of Lymnaea stagnalis L. and the effect of cadmium on the natural zinc level

The uptake of cadmium (0.1 mg/L) into various organs of the pond snailLymnaea stagnalis L., the depuration of accumulated Cd, and the change in the natural Zn level under the influence of Cd treatment were investigated during a 2 month period. The snails were fed with lettuce (Latuca sativa). The concentrations of Cd were measured in the whole soft body, various organs (liver, viscera, foot), the shell and the lettuce; and zinc concentrations were measured in various organs and the lettuce. As its Cd concentration remained at 10 μg/g, which was much lower than the initial value for the soft body (69.4±5.71 μg/g), the shell, according to our results, is incapable of accumulating Cd. The uptake pattern of the soft body showed a correlation with the initial Cd levels depending on differences in the Cd concentration of the lettuce. At the higher initial value (69.4±5.71 μg/g) the linear Cd uptake began later then it did at the lower initial value; afterwards the snail was saturated with Cd. In the case of the lower, 9.02±1.3 μg/g initial concentration, a rapid linear Cd uptake occurred till the 7th day, then the intensity of the uptake decreased. Saturation occurred at 200 μg/g Cd concentration, regardless of the initial value. At the lower initial tissue level, the foot and the viscera showed a linear uptake pattern, while the liver, which has the greatest accumulation ability, displayed a logarithmic uptake pattern. The initial and the final Cd concentrations in the foot, viscera, and liver of theL. stagnalis were as follows: 10.3±2.15−60.1±7.13, 5.15±1.04−156±27.2, 14.1±3.09−430±23.3 μg/g respectively. The bioconcentration factors (CF) were in the 102 (foot) and 103 (viscera, liver, soft body) orders of magnitude. Forty to 45% of the accumulated Cd was depurated in Cd-free tap water; during the first three days of the uptake period, a negative linear correlation was found between Cd and Zn levels in the snail organs.

Heavy metal concentrations of Lymnaea stagnalis L. in the environs of lake Balaton (Hungary)

Abstract The concentrations of eight heavy metals (Cr, Cd, Hg, Pb, Zn, Cu, Mn and Fe) were determined for the total soft body of pond snails ( Lymnaea stagnalis L. Gastropoda, Pulmonata) originating from four different biotopes in the environs of Lake Balaton, using atomic absorption spectrophotometry. The concentration of toxic metals (Cr, Cd, Hg, Pb) showed linear decreasing tendency with the increase in body weight. For the biogenic metal concentration, no decreasing correlation was detected with the body weight, however, the metal content (Zn, Cu, Mn, Fe) was found to significantly increase ( P P Lymnaea stagnalis L. reflect differences in the pollution of the environment.

Comparison of mussels and crustacean plankton to monitor heavy metal pollution

The ability of freshwater organisms (mussels — Unio pictorum L. and crustacean plankton —Cladocera and Copepoda species) to monitor heavy metal pollution was compared under field conditions, near the effluent discharge of a sewage water treatment plant at Lake Balaton (Hungary). The mussels were transferred from their less polluted habitat to the study area. The crustacean plankton was collected at this site The concentrations of Hg Cd Cr Cut Pb, Zn, and Fe were measured m the gills of the transplanted mussels as well as the natural zooplankton in the summer period, using the AAS method. Both mussel gills and the zooplankton showed periodically high Fe-, Zn-, and Cu-concentrations. An elevated level of Hg was only observed in mussels, while high Pb- and Cr-concentrations were found only in crustacean plankton. Accordingly the zooplankton seems a more suitable model for monitoring heavy metal pollution under these field conditions.